Fix Python lint and unit tests

One of the unit tests added in
https://webrtc-codereview.appspot.com/50079004/ is failing
on Windows since os.sep is a backslash on Windows.
The code is based on the contents of the DEPS file rather than
the filesystem, so the right thing is to use '/' instead of os.sep.

The PyLint blacklist also didn't work on Windows, causing it
to process a massive list of files during presubmit.

I also added a bunch of new entries to speed up lint execution on
all platforms.

TESTED=Ran the presubmit with this CL on Windows and Linux.
R=phoglund@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/52029004

Cr-Commit-Position: refs/heads/master@{#9353}

PRESUBMIT.py

@@ -257,24 +257,30 @@ def _CommonChecks(input_api, output_api):
       black_list=(r'^.*gviz_api\.py$',
                   r'^.*gaeunit\.py$',
                   # Embedded shell-script fakes out pylint.
-                  r'^build/.*\.py$',
-                  r'^buildtools/.*\.py$',
-                  r'^chromium/.*\.py$',
-                  r'^out.*/.*\.py$',
-                  r'^testing/.*\.py$',
-                  r'^third_party/.*\.py$',
-                  r'^tools/clang/.*\.py$',
-                  r'^tools/gn/.*\.py$',
-                  r'^tools/gyp/.*\.py$',
-                  r'^tools/protoc_wrapper/.*\.py$',
-                  r'^tools/python/.*\.py$',
-                  r'^tools/python_charts/data/.*\.py$',
-                  r'^tools/refactoring/.*\.py$',
-                  r'^tools/swarming_client/.*\.py$',
+                  r'^build[\\\/].*\.py$',
+                  r'^buildtools[\\\/].*\.py$',
+                  r'^chromium[\\\/].*\.py$',
+                  r'^google_apis[\\\/].*\.py$',
+                  r'^net.*[\\\/].*\.py$',
+                  r'^out.*[\\\/].*\.py$',
+                  r'^testing[\\\/].*\.py$',
+                  r'^third_party[\\\/].*\.py$',
+                  r'^tools[\\\/]find_depot_tools.py$',
+                  r'^tools[\\\/]clang[\\\/].*\.py$',
+                  r'^tools[\\\/]generate_library_loader[\\\/].*\.py$',
+                  r'^tools[\\\/]gn[\\\/].*\.py$',
+                  r'^tools[\\\/]gyp[\\\/].*\.py$',
+                  r'^tools[\\\/]protoc_wrapper[\\\/].*\.py$',
+                  r'^tools[\\\/]python[\\\/].*\.py$',
+                  r'^tools[\\\/]python_charts[\\\/]data[\\\/].*\.py$',
+                  r'^tools[\\\/]refactoring[\\\/].*\.py$',
+                  r'^tools[\\\/]swarming_client[\\\/].*\.py$',
+                  r'^tools[\\\/]vim[\\\/].*\.py$',
                   # TODO(phoglund): should arguably be checked.
-                  r'^tools/valgrind-webrtc/.*\.py$',
-                  r'^tools/valgrind/.*\.py$',
-                  r'^xcodebuild.*/.*\.py$',),
+                  r'^tools[\\\/]valgrind-webrtc[\\\/].*\.py$',
+                  r'^tools[\\\/]valgrind[\\\/].*\.py$',
+                  r'^tools[\\\/]win[\\\/].*\.py$',
+                  r'^xcodebuild.*[\\\/].*\.py$',),
       disabled_warnings=['F0401',  # Failed to import x
                          'E0611',  # No package y in x
                          'W0232',  # Class has no __init__ method

tools/autoroller/roll_chromium_revision.py

@@ -182,9 +182,9 @@ def GetMatchingDepsEntries(depsentry_dict, dir_path):
     if path == dir_path:
       result.append(depsentry)
     else:
-      parts = path.split(os.sep)
+      parts = path.split('/')
       if all(part == parts[i]
-             for i, part in enumerate(dir_path.split(os.sep))):
+             for i, part in enumerate(dir_path.split('/'))):
         result.append(depsentry)
   return result